The present invention relates to programming/diagnostic devices for use with implantable programmable medical devices, such as pacemakers. More particularly, the present invention relates to specific improvements of pro-programming/diagnostic devices that (i) facilitate noninvasive communications with an implantable programmable pacemaker, and (ii) permit both real-time and prospective analysis of the pacemaker operation as it interacts with the heart.
In the past, the primary source of diagnostic data for use in analyzing the operation of an implanted pacemaker has been the surface electrocardiogram (ECG), in which both pacemaker and heart activity are blended. From the ECG, the activity of the heart--including the contraction of the atria, the contraction of the ventricles, and the timing therebetween--could be displayed. From the pacemaker, the activity of the pacemaker--including when a heart contraction was sensed and when a stimulating pulse was generated--could likewise be monitored through the use of marker signals telemetered from the pacemaker to a remote (non-implanted) receiver, where such signals were processed and displayed as marks on the ECG waveform.
In recent years, some implantable pacemakers have included the capability of transmitting an intercardiac ECG signal, either alone or in combination with marker signals, thereby allowing a complete analysis of the interaction of the heart with the pacemaker without the need of first obtaining surface ECG signals. See, e.g., U.S. Pat. No. 4,559,947. Pacesetter Systems, Inc., of Sylmar Calif., has in recent years provided a programming system for use with implanted pacemakers called an Analyzer-Programmer System (APS). The APS, when noninvasively coupled to an implanted pacemaker, and when also connected to conventional skin ECG electrodes, is capable of selectively displaying either the surface ECG or the intercardiac ECG with event and timing annotation of pacemaker activity. U.S. Pat. No. 4,596,255 describes some of the display and processing features of the APS. These features have greatly enhanced the ability to properly diagnose the interaction between pacemaker and patient. That is, by using an APS, a doctor, cardiologist, or other diagnostician can readily decipher the source of stimulating pulses, the response or lack of response of the heart to such pulses, the existence and duration of refractory periods, and the like. Such capability has proven especially useful in understanding and analyzing the complex operation of dual chamber pacemakers.
Unfortunately, while the APS and similar programming/diagnostic systems, such as those described in U.S. Pat. Nos. 4,208,008, 4,417,306, and 4,505,276, have done much to facilitate communications with and analysis of implantable programmable pacemakers, such systems typically require extensive training and experience on the part of their users before they can be used effectively. Like many microprocessor-based systems (e.g. personal computers), such systems can at times be very frustrating for the user unless the user is intimately familiar with the correct sequence of instructions that must be provided to invoke a desired response.
Moreover, where the principal operating parameters of the pacemaker are programmable (as is the case with most modern pacemakers), and particularly where the operation of a dual chamber pacemaker is being analyzed (a dual chamber pacemaker is one that is capable of sensing and/or pacing in both chambers of the heart), it has often been difficult for the user of the programming/analyzer system to know what the reaction of the heart will be or should be to a given programming change. This is because of the relatively large number of variables that can be involved in dual chamber pacing, each variable having potential of interacting with the others in affecting the overall operation of the pacemaker. With such a large number of variables, it is difficult for the user of the system to keep track of all possible interactions. Similarly, even when the programming/analyzer system provides or displays needed information, such as the values of selected variables or parameters, such information has not always heretofore been provided or displayed in a format that makes it easy to understand and use in relation to other known information.
Further, as the amount of information being transferred between such programmer/analyzer systems and the pacemaker has increased, the complexity, and hence the cost, of such systems has also increased. In some instances, the cost of such systems may be prohibitive, thereby necessitating the use of less complex programmer/analyzer systems that do not offer the full capabilities that are technologically available with the more complex programmer/analyzer systems.
What is needed therefore, is a programmer/analyzer system for use with implantable programmable pacemakers that offers all needed communication and diagnostic capabilities, yet is easy to use and understand, and is less costly to build. The present invention addresses these and other needs.